So you're saying that you'll do the actual work now, while you are drawing benefits, but not be paid for it until September. For unemployment purposes, that is a way to do it, but it won't do anything much for you, in my opinion. In truth, it wouldn't be any different than committing fraud. Because the words of the weekly certifications for benefits are something like, 'Did you do any work this week for which you were paid, or will be paid at some future date." No way to duck it, that's what they're talking about. Pick up work, not for covered employers is generally okay, but if you've got a lot of work going on, it very well may come up.
I'd suggest you keep it honest, instead of trying to fancy it up. Okay, there's not so much point in doing a job for which you won't be paid till Christmas in order to "support myself." The idea of unemployment insurance is that you are supposed to be supporting yourself and living on it. But If you have the necessity of doing freelance jobs, then report them honestly at the time you put in the hours, as in 8-10 hours a calendar week (which is how unemployment calculates work week, regardless of when you'll be paid.)
Reporting the money won't reduce your benefits really, it just deducts a certain amount (not, incidentally, penny for penny as you said) from your WBA because of the work you have done that week. If you never make more than your Weekly Basic Amount in gross wages, not net, it will not stop your claim. If you do go over the amount, it will stop your claim and you will have to reopen the claim to file for the next week. And that money that is deducted is not lost, it's just added back onto your total amount of unemployment you can draw eventually. I saw lots of people who did freelance things like work as an adjunct instructor, paid one time a year. They reported their amount at the time the work was done, 2-3 hours a week, which did not reduce their weekly basic amount much at all, yet did honestly cover the earnings that later showed up when the system cross matched their benefits with their reported income on their income taxes.
